Logistic regression analysis showed that the presence or absence of vomiting (P=0.013) and mucositis (P=0.005) was significantly correlated with heterozygous mutation of UGT1A1*28, and the severity of vomiting (P < 0.001) and neutropenia (P=0.021) were significantly correlated with heterozygous mutation of UGT1A1*6. Here, UGT1A1 is linked to mucositis.